The present disclosure is related to an optical transmitting device. More particularly, the present invention provides an improved 1550 nm DFB laser diode package on a submount sharing the cold side of a built-in thermoelectric cooling module with an assembly of an aspherical optical coupling lens. Processes for assembling the optical transmitting device are also disclosed.
As science and technology are updated rapidly, processing speed and capacity of the computer increase correspondingly. The communication transmission or reception using the traditional cable is limited to bandwidth and transmission speed of the traditional cable and mass information transmission required in modern life causes the traditional communication transmission overload. To correspond to such requirement, the optical fiber transmission system replaces the traditional communication transmission system gradually. The optical fiber transmission system does not have similar bandwidth limitations, and also has advantages of higher speed transmission, longer transmission distance, its material is not susceptible to the electromagnetic interference. Therefore, present electronic industry performs research in optical fiber transmission which will become the mainstream in the future. Said optical communication is a technology in that light functions as signal carrier and is transmitted between two nodes via the optical fiber. Field of the optical communication can be divided into optical communication side and electrical communication side according to the transmission medium. By the optical transceiver, the received optical signal can be converted to an electrical signal capable of being processed by an IC, or the processed electrical signal can be converted to the optical signal to be transmitted via optical fiber. Therefore, objective of communication can be achieved.
Wavelength-division multiplexing (WDM) is a multitask technology of processing multiple optical carrier signals transmitted by the optical fiber, and this technology is applied on the different wavelengths of laser optical signal. Besides, the term “wavelength-division multiplexing” is mostly applied in optical carrier, and frequency-division multiplexing is applied in radio carrier. Moreover, both of wavelength and frequency are in reciprocal relationship, so their concept can be applied to each other.
Wavelength-division multiplexing is implemented by dividing the data channel into multiple wavelengths in the optical fiber to enable mass data transmission in one optical fiber. The complete wavelength-division multiplexing (WDM) system can be implemented by a wavelength division multiplexer at transmitting end and a wavelength division demultiplexer at receiving end. At present, there are commercial wavelength division multiplexer/demultiplexer which can combine/divide 80 or more channels in the optical fiber communication system, so that the data transmission speed can exceed multiple Tb/s effectively.
In the transmitting module adapted for WDM technology, the connector usually has single light transmitter structure. However, such light transmitter structure can emit optical signal with preset frequency which usually lacks stability and often drifts away from the preset wavelength during environmental temperature changes. Although adding thermoelectric cooler module to the transmitting device is known, an improved package integrating a thermister, a thermoelectric cooler (TEC) module, and a laser diode (LD) chip on a submount sharing a common code side of the TEC module with an aspherical optical coupling lens is still highly desired for enhancing control of operation temperature, wavelength stability, and LD-to-fiber coupling efficiency of emitted light especially in 1310 nm or 1550 nm DWDM channels.